Hmmm.. I should add a few things:
SKIP has a function, you just mentioned it: Actually, its got no function apart from being used with HINT - so err.. Yea.
and can be toggled off (+a).
Toggles can have 10 frames too, (a,b,c,d,e,f,g,h,i,j,k) so, you can make a looping animation with 20 frames if you're smart with the entities.
Random tiling: Yep, kinda sucky, but depends on the texture.
Only textures that have the "-0texturename" texture get randomly tiled in the game. If you have "-2texturename" on a face, it won't be randomly tiled.
Water textures: Always full bright in the game
But you can fake a few things.
The "fog" colour and density is defined with the texture colours: Index[4] colour must be a shade of red, the redder it is, the mode dense the fog.
The index[3] is the fog colour. I
think that's right... you may need to experiment and look at existing water textures.
Scroll textures: if you need to change the direction of the scroll rotate the texture (from the texture app. tool, not from the little compass for the entity properties)
And "{texturename" textures: The textures with the blue, set the render properties to Solid, render amt. to 255 to make the blue parts invisible, in the actual texture, you must have the blue a PURE blue (0 0 255) and it has to be the last Index colour in a 256 colour pal. (basically, the last colour in the pal.)